Influence of hydrogen on the electrical properties of Pd/InP structures

The influence of hydrogen on the electrical properties of Pd/$n$-InP and Pd/oxide/$n$-InP structures is studied. It is found that a variation in the cutoff voltage $\Delta U_{\operatorname{cut-off}}$ in the current–voltage characteristics of the structures under study upon exposure to hydrogen with concentrations of 0–1 vol % in a nitrogen–hydrogen mixture is described by the exponential dependence: $\Delta U_{\operatorname{cut-off}}=a[1-\operatorname{exp}[-b\cdot N_{\mathrm{H}}$], where $N_{\mathrm{H}}$ is the hydrogen concentration (vol %), and $a$ and $b$ are constants dependent on the type of structures. It is shown that a decisive influence on how the potential-barrier height changes in the Pd/InP and Pd/oxide/InP structures in the presence of H$_2$ in a gas medium is exerted by a change in the Pd work function in an atmosphere of hydrogen. It is found that, in the structures under study, tunneling and thermal-tunneling charge-transport mechanisms operate at 90–300 K in the presence of hydrogen and without it. With increasing hydrogen concentration in the gas mixture, the predominance of the tunneling charge-transport mechanism becomes more pronounced.